JPH0268564A - electrophotographic photoreceptor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a novel electrophotographic photoreceptor.
More specifically, the present invention relates to an electrophotographic photoreceptor containing a bisazo pigment having a specific molecular structure in a photoconductive layer.

[Conventional technology]

As shown in U.S. Pat. No. 2,297,691, electrophotography uses a light guide using a support coated with an insulating material in the dark, the electrical resistance of which changes depending on the amount of radiation received during one exposure. Use Buddhist materials. The basic characteristics of electrophotographic photoreceptors using light-conducting materials include (1) the ability to be charged to an appropriate potential in the dark; and (2) the ability to charge to an appropriate potential in a dark place.
(3) There is little charge dissipation in a dark place; and (3) the scales dissipate charge quickly when irradiated with light.

Conventionally, inorganic photoreceptors having photosensitive layers containing inorganic light-conducting compounds such as selenium, zinc oxide, cadmium sulfide, etc. as main components have been widely used as photoreceptors. However, although these satisfy the conditions (1) to (3) above, they do not necessarily satisfy conditions such as thermal stability, moisture resistance, and durability. For example, when selenium crystallizes, its properties as a photoreceptor deteriorate, making it difficult to manufacture.Also, selenium crystallizes due to heat, fingerprints, etc., and its performance as a photoreceptor deteriorates. Furthermore, cadmium sulfide has problems with moisture resistance and durability, and zinc oxide has problems with smoothness, hardness, and abrasion resistance. Furthermore, many inorganic photoreceptors have a limited photosensitive wavelength region. For example, selenium is sensitive to wavelengths in the true color range, with almost no sensitivity in the red range. For this reason, various methods have been proposed to extend photosensitivity to longer wavelength ranges, but there are many restrictions on the selection of the sensitive wavelength range.Even when zinc oxide or cadmium sulfide is used as a photoreceptor, the sensitivity wavelength range of the material itself is limited. is narrow and requires the addition of a large amount of sensitizer.

In order to overcome these drawbacks of inorganic photoreceptors, electrophotographic photoreceptors containing various organic photoconductive compounds as main components have been actively developed in recent years. For example, Tokko Sho 50-1
No. 0496 and US Pat. No. 3,484,237 disclose a photoreceptor having a photosensitive layer containing poly-N-vinylcarbazole and 2.4.7-)dinitrofluorenone-9-one, /! There are nine types of J-N-vinylcarbazole sensitized with pyrylium salt dyes (Japanese Patent Publication No. 48-25658). Although these organic electrophotographic photoreceptors have improved the drawbacks of the inorganic electrophotographic photoreceptors to some extent, they generally have low photosensitivity and are not suitable for repeated use. In order to overcome these drawbacks, various photoreceptors have been proposed as organic electrophotographic photoreceptors in recent years. Among them, materials that generate charge carriers when irradiated with light (hereinafter referred to as
A layer (hereinafter referred to as charge generation layer) containing a charge generation material (hereinafter referred to as a charge generation substance) and a layer (hereinafter referred to as Compared to conventional organic electrophotographic photoreceptors, laminated photoreceptors consisting of a charge transport layer (called a charge transport layer) have been put into some practical use because they are generally more sensitive and can withstand repeated use. There is something.

For example, U.S. Pat. No. 3,878,851 discloses a photoreceptor having a charge generation layer and a charge transfer layer containing triallylpyrazoline, and U.S. Pat. Examples include a photoreceptor comprising a charge transfer layer made of a formaldehyde condensate.

Further, a photoreceptor using a bisazo pigment or a trisazo pigment as a charge generating substance is disclosed in Japanese Patent Application Laid-Open No. 59-33445,
JP-A-56-46237, JP-A-60-1112
This is already known in Publication No. 49 and the like. However, these bisazo pigments or trisazo pigments are not necessarily satisfactory in terms of sensitivity, residual potential, or stability of potential characteristics during repeated use, and the selection range of charge transport materials is also limited, making it difficult for electrophotographic processes. It did not fully satisfy a wide range of demands.

In addition, bisazo pigments having a carbonyl compound group in the central skeleton are disclosed in JP-A-54-22834 and JP-A-56-1.
43437 and JP-A-57-138646, these bisazo pigments have high sensitivity,
The stability of the potential characteristics during repeated use is not necessarily satisfactory, and the sensitivity in the near-infrared region in particular is not sufficient.

On the other hand, in recent years, these organic photoconductors have been
There has been a rapid increase in the demand for extending the photosensitive wavelength range to around 00 nm (the most preferred in terms of economy, output, matching with photosensitive materials, etc.) and for use as photoreceptors for digital recording such as laser printers. Considering conventional organic photoconductors from this point of view, US Pat. No. 4,426,434
Aluminum phthalocyanine pigments shown in US Pat. No. 4,436,800 and US Pat. No. 4,439,506, tetrakisazo pigments shown in US Pat. proposed as a body.

However, when using an organic photoconductor as a photoreceptor for semiconductor radar, firstly, the photosensitive wavelength range must extend to long wavelengths, secondly, the sensitivity and durability must be good, and the Since the wavelength of semiconductor radar changes, it is necessary to have constant sensitivity over a wide wavelength range, stable potential characteristics even with repeated use, and good productivity. . The organic photoconductor described above does not fully satisfy these conditions.

[Problem to be solved by the invention]

A first object of the present invention is to provide a novel electrophotographic photoreceptor.

A second object of the present invention is to provide an electrophotographic photoreceptor having practical high sensitivity characteristics in the visible region and stable potential characteristics upon repeated use.

A third object of the present invention is to provide a novel photoconductor for near-infrared light, and a fourth object of the present invention is to provide a novel photoconductor for use in digital recording such as laser copiers, radar beam printers, LED printers, etc. The object of the present invention is to provide an electrophotographic photoreceptor that has practical high sensitivity characteristics and stable potential characteristics during repeated use.

[Means to solve the problem]

The problem is to provide an electrophotographic photoreceptor having a photosensitive layer containing an azo pigment on a conductive support, in which the azo pigment has the general formula: The problem was solved by an electrophotographic photoreceptor characterized by being a compound represented by the following formula (representing all residues).

A and A' in the general formula (1) represent Kab2-residues having a phenolic OH group, and preferred specific examples of Kab2-residues represented by A and A' are those of the general formulas (2) to (8). ).

X in formula (2) is fused with a benzene ring to form a 67 talene ring,
Represents a residue necessary to form a polycyclic aromatic ring or heterocycle such as an anthracene ring, carbazole ring, benzcarbazole ring, dibenzofuran ring, dibenzonaphthofuran ring, and sophenylene sulfite ring.

The ring to which X is bonded is more preferably a naphthalene ring, an anthracene ring, a carbazole ring, or a benzcarbazole ring.

In formula (2), R and R2 represent a hydrogen atom, an alkyl group that may have a substituent, an aryl group, an aralkyl group, or a heterocyclic group, and R1 and R2 represent a cyclic amine group together with a nitrogen atom. Specific examples of alkyl groups that may be formed include methyl, ethyl, propyl, butyl, etc., specific examples of aralkyl groups include benzyl, phenethyl, naphthylmethyl, etc., and specific examples of aryl groups include phenyl, diphenyl, Specific examples of the heterocyclic group include naphthyl, anthryl, etc., and carbazole, dibenzofuran, benzimidacylone, benzthiazole, thiazole, pyridine, etc.

R5 in the general formulas (3) and (4) represents a hydrogen atom, an alkyl group that may have a substituent, an aryl group, an aralkyl group, specifically, methyl, ethyl, propyl, isopropyl, Butyl, l@C-butyl, t-butyl, phenyl, p-tolyl, benzyl, 7-enethyl, naphthylmethyl, etc.

The alkyl group, aryl group, aralkyl group, and heterocyclic group represented by the substituents R1 to R5 in formulas (2) to (4) may further include other substituents such as halogen groups such as fluorine, chlorine, iodine, and bromine, methyl, Alkyl groups such as ethyl, propyl, inpropyl, butyl, methoxy, ethoxy,! It may be substituted with an alkoxy group such as lopoxy or phenoxy, an allyloxy group, a nitro group, a cyano group, a substituted amine group such as dimethylamino, nobenzylamino, diphenylamino, morpholino, piperidino, or pyrrolidino.

, Yl In formulas (5) and (6), Y represents a divalent aromatic hydrocarbon group or a divalent heterocyclic group having a nitrogen atom in the ring.

Examples of divalent groups of aromatic hydrocarbons include divalent groups of monocyclic aromatic hydrocarbons such as O-phenylene, o-su7? L/n,
Perinaphthylene, 1,2-antrylene, 9.10-7
Examples include divalent groups of fused polycyclic aromatic hydrocarbons such as enanthrille/etc. Also, 2 of a heterocycle containing a nitrogen atom in the ring
As the valent group, 3,4-pyrazolediyl group 2,3-
pyridinediyl group, 4.5-pyrimidinediyl group, 6,
Divalent groups such as 7-indazolediyl group and 6,7-chiralindiyl group can be mentioned.

H-Form General Formula X in formula (7) has the same meaning as X in formula (2). R5 represents an aryl group or a heterocyclic group which may have a substituent, and specifically represents a phenyl, naphthyl, anthryl, pyrenyl, pyridyl, thienyl, furyl, or carbazolyl group.

Substituents for the aryl group and heterocyclic group represented by R5 include halodane groups such as fluorine, chlorine, iodine, and bromine; alkyl groups such as methyl, ethyl, propyl, isopropyl, and butyl;
Examples include alkoxy groups such as methoxy, ethoxy, propoxy, and phenoxy, and substituted amine groups such as allyloxy, nitro, cyano, dimethylamino, dibenzylamino, diphenylamino, morpholino, piperidino, and pyrrolidino.

85 in formula (8). R6 represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent, specifically methyl, ethyl, propyl, butyl, benzyl, phenethyl, naphthylmethyl, phenyl, Naphthyl, anthryl, diphenyl, carbazole, dibenzofuran, benzimidazolo/, benzthiazole, thiazole, pyridi/.

Substituents for the alkyl group, aryl group, aralkyl group, and heterocyclic group represented by R51R6 in formula (8) include fluorine, chlorine, iodine, bromine, etc., methyl, ethyl,
Alkyl groups such as propyl, inpyropyl, and butyl; alkoxy groups such as methoxy, ethoxy, propoxy, and phenoxy; substituted amine groups such as allyloxy, nitro, cyano, dimethylamino, diinzolamino, diphenylamino, morpholino, piperidino, and pyrrolidino; Can be mentioned.

Specific examples of the azo pigment represented by the general formula (1) are listed below.

A general method for producing the bisazo pigment of general formula (1) used in the present invention will be described. When A and A' are the same in the bisazo pigment represented by the general formula (1), the following general formula (9) is used.
The diamine represented by is converted into a sidiazonicum salt by a conventional method using sodium nitrite or nitrosyl sulfuric acid, and then aqueous coupling is performed with the coupler components A and A', or the resulting diazonium salt is converted into a stable borofluoride salt or the like. It can be obtained by extracting it as a salt and then coupling it in an organic solvent such as dimethylformamide.

If A and A' are different, in the coupling reaction, first couple with the first coupler component to form a heptanoazo compound, and then couple with the second coupler component to form a bisazo pigment, or It can be obtained by mixing two coupler components and performing a coupling reaction.

General formula (9) Next, a synthesis example of the disazo pigment used in the present invention will be given.

Synthesis Example (Synthesis of Disazo Pigment A3 as exemplified above) 150 ml of concentrated hydrochloric acid and 15.11 (0,032 mol) of cyanide of general formula (9) were placed in a 300-sized gobeaker, cooled to 0°C, and 4.61 ml of sodium nitrite was added. ! (0,067mol
) was dissolved in 10ml of water and dropped into the solution over 10 minutes while keeping the temperature of the solution below 5°C. After stirring for 15 minutes, a solution of 10.5# (0,096 mol) of sodium borofluoride dissolved in 90117 water was poured into the solution under stirring, and the precipitated borofluoride salt was collected by P. The mixture was washed with cold water, washed with acetonitrile, and dried under reduced pressure at room temperature. Yield i 1.7 g #Yield 63.4 g Next, add N,N-dimethylform 7mide (D
MF) 500- and 10.5 g (0,042 mol) of 3-phenylcarbamoyl-2-naphthol
After dissolving the solution and cooling the liquid temperature to 5°C, 11.5 g (0,020 mol) of the previously obtained borofluoride salt was dissolved, and then 5.1 K (0,050 mol) of triethylamine was dissolved.
) was added dropwise over 5 minutes. After stirring for 2 hours, the precipitated pigment was collected, washed four times with DMF and three times with water, and then freeze-dried. Yield 16.3g, yield 79.8g Coating methods include dip coating method, spray coating method, spinner coating method, bead coating method, Mayer coating method, blade coating method, roller coating method, curtain coating method, etc. This can be done using the following coating method. For drying, it is preferable to dry to the touch at room temperature and then heat dry. Heat drying can be carried out at a temperature of 30° C. to 200° C. for a period of time ranging from 5 minutes to 2 hours, either stationary or under ventilation.

The charge transport layer is electrically connected to the charge generation layer described above, and has the function of receiving and taking charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. have. In this case, the charge transport layer may be located on the side farther from the charge generation layer when viewed from the conductive support, or may be located between the conductive substrate and the charge generation layer.

When the charge transport layer is formed on the side far from the charge generation layer when viewed from the conductive substrate, the substance that transports charge carriers in the charge transport layer (hereinafter simply referred to as charge transport substance) is
The "electromagnetic waves" referred to herein are preferably substantially insensitive to the wavelength range of electromagnetic waves to which the charge generation layer is sensitive.
What is rlfiA?

Includes a broad definition of "light" that includes X-rays, ultraviolet rays, visible light, near-infrared rays, infrared rays, far-infrared rays, and the like. When the photosensitive wavelength range of the charge transport layer matches or overlaps that of the charge generation layer, specific charge carriers generated in the two trap each other, resulting in a decrease in sensitivity.

Charge transporting substances include electron transporting substances and hole transporting substances, and electron transporting substances include chloranil, chromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4.7-)dinitro-9. -Fluorenone, 2,4,5.7-tetranitro-9-fluorenone, 2,4.7-) dinitro-9-dicyanomethylenefluorenone, 2.4.5.7-titranitroxanthone%2#4t8-)' ) There are electron-withdrawing substances such as nidrothioxanthone, and polymerization of these electron-withdrawing substances.

Examples of hole-transporting substances include pyrene, N-ethylcarbasol% N-isoglobilcarpazole, N-methyl-N
-7enylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N,N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, N, N-diphenylhydrazino-3-methylidene-10-ditylphenoxazine, p-diethylaminebenzaldehyde-N,N-diphenylhydrazone.

p-diethylaminobenzaldehyde-N-α-naphthyl-N-7enylhydrazone, p-pyrrolidinobenzaldehyde-N,N-diphenylhydrazone, 1.3.3
-) Dimethylindolenine-ω-aldehyde-N,N
-Diphenylhydrazino, hydrazones such as p-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, 1- Phenyl-3-(p-diethylaminostyryl)-5-(p-
diethylaminophenyl)pyrazoline, 1-[quinolyl(2))-3-(p-diethylaminostyryl)-
5-(p-diethylaminophenyl)pyrazoline, l-
[Pyridyl<2) -3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)hilazoline, 1-(6-medoxypyridyl(2)) -3
-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl (3)
) -3-(p-diethylaminostyryl)-5-(
p-diethylaminophenyl)pyrazoline, 1-(lepidyl (2) :l -3-(p-diethylaminostyryl)-5-(P-diethylaminophenyl)pyrazoline, 1-(pyridyl(2))]-3-(p- Diethylaminostyryl-4-methyl-5-(p-diethylaminophenyl)pyrazoline, 1-[pyridyl(2))-3-
(,α-methyl-p-diethylaminostyryl)-5-
(p-diethylaminophenyl)pyrazoline, 1-7enyl-3-(p-diethylaminostyryl)-4-methyl-5-(p-diethylaminophenyl)pyrazoline,
Pyrazolines such as l-7enyl-3-(α-benzyl-p-diethylaminostyryl)-5-(p-diethylaminophenyl)hilazoline and spiropyrazoline, α
-Phenyl-4-N, N-nobuenylaminostilbene, N-ethyl-3(α-phenylstyryl)carbazole, 9-p-dipenzolaminopene solidene-9H-fluorenone, 5-p-ditolyl amino Benzylidene-5
Styryl compounds such as H-dipenzo(a,d)cycloheptene, 2-(p-diethylaminostyryl)-6-
Oxazole compounds such as dinithylaminobenzoxazole #, 2-(p-diethylaminophenyl)-4-(p-dimethylaminophenyl)-5-(2-chlorophenyl)oxazole, 2-(p-diethylaminostyryl)- Thiazole compounds such as 6-diethylaminobenzothiazole, triarylmethane compounds such as bis(4-diethylamino-2'-methylphenyl)-phenylmethane, 1,1-bis(4-N,N-diethylamino-2-methyl polyarylalkane such as phenyl)hebutane, 1,2,2-tetrakis(4-N,N-dimethylamino-2-methylphenyl)ethane, triphenylamine, poly-N-vinylcarbazole, 4-rivinylpyrene , polyvinylanthracene, polyvinylacrysine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, ethylcarbazole formaldehyde resin, and the like.

In addition to these organic charge transport materials, inorganic materials such as selenium, selenium-tellurium amorphous silicon, and cadmium sulfide can also be used.

Further, these charge transport substances can be used alone or in combination of two or more.

When the charge transport material does not have film-forming properties, a film can be formed by selecting an appropriate binder. Examples of resins that can be used as binders include acrylic resin,
Polyarylate, polyester, polycar? nate, polystyrene, acrylonitrile-styrene; polymer,
Acrylonitrile-butadiene copolymer Insulating resins such as polyvinyl butyral, polyvinyl formal, polysulfone, polyacrylamide, polyamide, chlorinated rubber, or organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylant-2cene, polyvinylpyrene, etc. can be mentioned.

A coating containing the bisazo pigment of the general formula (1) described above exhibits photoconductivity and can therefore be used in the photosensitive layer of an electrophotographic photoreceptor.

That is, in the present invention, the bisazo pigment of the general formula (3) is formed on a conductive substrate by vacuum evaporation, or dispersed in a suitable binder to form a film. can form a body.

In a preferred embodiment of the present invention, the above-mentioned film exhibiting photoconductivity is applied as a charge generation layer in an electrophotographic photoreceptor in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer. Can be done.

The charge generation layer contains as much of the above-mentioned photoconductive compound as possible in order to obtain sufficient absorbance, and is a thin film layer, for example, 5 μm or less, in order to shorten the range of the generated charge carriers. , preferably a thin film layer having a thickness of 0.01 to 1 μm. This means that most of the incident light is absorbed by the charge generation layer, generating many charge carriers, and that the generated charge carriers are transported by recombination or trapping without being deactivated. This is due to the need to inject into the layer.

As described above, the charge generation layer can be formed, for example, by dispersing the bisazo pigment of Formation (1) in a suitable binder and coating it on the substrate, or by applying the vapor-deposited film using a vacuum vapor deposition apparatus. It can be obtained by forming The binder that can be used to form the charge generating layer by coating can be selected from a wide variety of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene. Preferably, -rivinyl petyral, polyarylate (condensation polymer of bisphenol A and heptalic acid, etc.), polycarbonate, etc. Insulating resins such as ester, polyester, phenoxy resin, divinyl acetate, acrylic resin, polyacrylamide resin, polyamide, polyvinylgiridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, polyvinylpyrrolidone, etc. Can be done. The resin contained in the charge generation layer is suitably 80% by weight or less, preferably 40% by weight or less.

The solvent that dissolves these resins varies depending on the type of resin, and it is preferable to select one from among those that do not dissolve the underlying charge transport layer or subbing layer. Specific organic solvents include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, amides such as N,N-dimethylformamide, N,N-tumethylacetamide,
Sulfoxides such as trimethyl sulfoxide, ethers such as tetrahydro7rane, dioxane, ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichloroethylene, etc. Aliphatic hydrogenated hydrocarbons or aromatic compounds such as benzene, toluene, xylene, lig-alphaine, monochlorobenzene, dichlorobenzene, etc. can be used.

Since the charge transport layer has a limit in its ability to transport charge carriers, it cannot be made thicker than necessary. Generally, it is 5 to 40 μm, but the preferred range is 15 to 2 μm.
It is 5 μm. When forming the charge transport layer by coating, an appropriate coating method as described above can be used.

A photosensitive layer having such a laminated structure of a charge generation layer and a charge transport layer is provided on a conductive substrate having, for example, a conductive layer. As a substrate having a conductive layer, use a material that has conductivity itself, such as 7# minium, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. In addition, it can be made of glass (e.g., polyethylene, boria-o-pyrene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoroethylene, etc.),
Conductive particles (e.g. carbon black, silver particles, etc.)
With appropriate considerations, a substrate coated on glass, a substrate made of plastic or paper impregnated with conductive particles, a plastic containing a conductive polymer, etc. can be used.

A subbing layer having barrier and adhesive functions can also be provided between the conductive layer and the photosensitive layer. Subbing layer, casein,
Polyvinyl alcohol, 2)0 cellulose, ethylene-
Acrylic acid copolymer, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin,
It can be formed from aluminum oxide, etc.

The thickness of the subbing layer is 0.05 to 5 μm, preferably 0.5 μm.
~3 μm is appropriate.

When using a photoreceptor in which a conductive layer, a charge generation layer, and a charge transport layer are arranged in this order, and the charge transport material is an electron transport material, the surface of the charge transport layer must be positively charged, and exposure after charging is required. Then, in the exposed area, electrons generated in the charge generation layer are injected into the charge transport layer, and then reach the surface and neutralize the positive charge, causing a decrease in surface potential and creating an electrostatic contrast with the unexposed area. . A visible image can be obtained by developing the electrostatic latent image thus formed with a negatively charged toner. This can be directly fixed, or the toner image can be transferred to paper, glass film, etc. and then developed and fixed.

Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or known methods, and are not limited to specific ones.

On the other hand, when the charge transport material consists of a hole transport material, it is necessary to negatively charge the surface of the charge transport layer. After charging, when exposed to light, specific pressure pores are generated in the charge generation layer in the exposed area, and specific pressure pores are formed in the charge transport layer. It is injected and then reaches the surface to neutralize the negative charges, resulting in attenuation of the surface potential and an electrostatic contrast between it and the unexposed area.

During development, it is necessary to use a positively charged toner, contrary to the case where an electron transporting substance is used.

When using a photoreceptor located at the top of a conductive layer, charge transport layer, or charge generation layer, if the charge transport material is an electron transport material, the surface of the charge generation layer must be negatively charged. When exposed to light, electrons generated in the charge generation layer in the exposed area are injected into the charge transport layer and then reach the conductive substrate.

On the other hand, holes generated in the charge generation layer reach the surface and the surface potential is attenuated, creating an electrostatic contrast with the unexposed area. A visible image can be obtained by developing the electrostatic latent image thus formed with a positively charged toner. This can be directly fixed, or the toner image can be transferred to paper, glass film, etc. and then developed and fixed. Alternatively, a method may be used in which the electrostatic latent image on the photoreceptor is transferred onto an insulating layer of transfer paper, then developed and fixed. The type of developer, the developing method, and the fixing method may be any known ones or methods, and are not limited to specific ones.

On the other hand, when the charge generation layer is made of a hole transporting substance, it is necessary to positively charge the surface of the charge generation layer, and when exposed to light after charging, the holes generated in the charge generation layer are injected into the charge transport layer in the exposed area. and then reaches the conductive substrate. On the other hand, the electrons generated in the charge generation layer reach the surface and the electrostatic potential is attenuated, creating an electrostatic contrast with the unexposed area. During development, it is necessary to use a negatively charged toner, contrary to the case where an electron transporting substance is used.

Further, in another specific example of the present invention, the above-mentioned hydrazones,
Organic photoconductive substances such as pyrazolines, styryl compounds, oxazoles, thiazoles, triarylmethanes, polyarylalkanes, triphenylamine, poly-N-vinylcarbazoles, zinc oxide, cadmium sulfide, selenium, etc. A photosensitive film can be obtained which contains the bisazo pigment of the above-mentioned general formula (1) as a sensitizer for the inorganic photoconductive substance. This photosensitive film is formed by coating these photoconductive substances and the bisazo pigment of general formula (1) described above together with a binder.

Another specific example of the present invention is an electrophotographic photoreceptor in which the above-mentioned bisazo pigment of general formula (1) is contained in the same layer together with a charge transport substance.

In this case, in addition to the above-mentioned charge transport substance, a charge transfer complex compound consisting of poly-N-vinylcarbashield trinitrofluorenone can be used.

The electrophotographic photoreceptor of this example can be prepared by dispersing the bisazo pigment of general formula (1) and the charge transfer complex compound in a solution of polyester dissolved in tetrahydrocufuran, and then forming a film thereon.

The pigment used in any of the photoreceptors contains at least one type of pigment selected from bisazo pigments represented by the general formula (1), and its crystal form may be amorphous or crystalline. In addition, if necessary, pigments with different light absorptions may be used in combination to increase the sensitivity of the photoreceptor, and two or more types of bisazo pigments represented by the general formula (1) may be combined for the purpose of obtaining a panchromatic photoreceptor. Alternatively, it can be used in combination with a charge generating substance selected from known dyes and pigments.

The electrophotographic photoreceptor of the present invention can be used not only for electrophotographic copying machines, but also for laser grinters and CRT printers.
It can also be widely used in electrophotographic applications such as ED printers, liquid crystal printers, and plate making.

〔Example〕

The present invention will be explained below with reference to Examples, but the embodiments of the present invention are not limited to these.

Examples 1 to 10 A 0.1 μm undercoat layer made of vinyl chloride-maleic anhydride-vinyl acetate copolymer resin was provided on an aluminum plate.

Next, the above-mentioned bisazo compound 11435. P was dissolved in cyclohexanone 951 with butyral resin (degree of butyralization: 63 mol %, number average molecular weight: 20,000) 2 Nt, and dispersed for 2 hours using a sandonl. This dispersion was applied onto the previously formed undercoat layer using a Mayer Par so that the film thickness after drying would be 0.5 μm, and dried to form a charge generation layer. Next, a hydrazone compound of the structural formula 511 and a polymethyl methacrylate resin (number average molecular weight 100,000) 5
& Chlorobenzene 70. The photoreceptor of Example 1 was prepared by dissolving n in d and coating it on the charge generation layer using a Mayer par so that the dry film thickness would be 20 μm and drying to form a charge transport layer. Photoreceptors corresponding to Examples 2 to 10 were prepared in exactly the same manner using other exemplary pigments shown in Table 1 in place of Bisazo Face Paint 3.

The electrophotographic photoreceptor fabricated in this way was manufactured by Kawaguchi Electric Co., Ltd.
Seiden Copying Paper Testing Equipment Mod@l 5P-428'f!
: The sample was statically charged with corona at -5.5 kV using a static method, held for 1 second in a dark place, and then exposed to light at an illuminance of 2 Lux to examine the charging characteristics. The charging characteristics are surface potential (vo) and 1
The exposure height (Ey) ft required for the potential to decay to the potential t-V when dark decaying for a second was measured. The results are shown in Table 1.

Examples 10 to 14 in Table 1 Using the photoreceptors used in Examples 1.6, 25.35, fluctuations in bright area potential and dark area potential during repeated use were measured. The method is to attach the photoreceptor to the cylinder of an electrophotographic copying machine equipped with a -5.6kV corona charger, exposure optical system, developer, transfer charger, static elimination exposure optical system, and cleaner. The structure is such that an image is obtained on the transfer paper as the transfer unit is driven. Using this copying machine, the initial bright area potential (vL) and dark area potential (Vo) are calculated as -
The light area potential (ML) and dark area potential (VD) were measured after being set at 200V and around -700V and used 5000 times. The results are shown in Table 2.

Example 15 2,4,7-dolinitro-9-fluorenone 51 and poly-44'-dioxydiphenyl-2,2'-propane carbonate (molecular weight 300, 000 ) 5 g to tetrahydrofuran 7
The coating amount after drying of the coating solution prepared by dissolving in 0d is 10
．． F/m'' and dried.

The electrostatic charge of the electrophotographic photoreceptor thus prepared was measured in the same manner as in Example 1. At this time, the charging polarity was set to ten. The results are shown below.

V: 69,600 volts Eq: 2.1 tux-s*c Example 16 A polyvinyl alcohol film having a thickness of KB1N of 0.51 Im was formed on the aluminum surface of an aluminum-deposited polyethylene terephthalate film. Next, the dispersion of the bisazo pigment used in Example 7 was applied onto the previously formed polyvinyl alcohol layer using a Mayer Par so that the film thickness after drying would be 05 μm, and dried to form a charge generation layer. Next, benzylidene compound 5I of the structural formula and bisphenol 2 type polycarbonate resin (viscosity average molecular weight 30,000) 5jl
A solution containing 32.5 RIK of t-monochlorobenzene was applied onto the charge generation layer so as to have a dry film thickness of 20 μm and dried to form a charge transport layer. The charging characteristics and durability characteristics of the photoreceptor thus prepared were measured in the same manner as in Example 1. The results are shown in Table 3.

vo: e690 volt E @1.2 tuxjs+ee stomach.

Table 3 (Durability characteristics) The results in Table 3 show that the sensitivity is good and the potential stability during long-term use is also good.

Example 17 5 of soluble nylon (6-66-610-12 quaternary nylon copolymer) was deposited on a 10011 m thick aluminum plate.
A methanol solution was applied and dried to form a subbing layer with a thickness of 0.5 μm.

Then 2.4.7-) dinitro-9-fluorenone 5I
and poly-N-vinylcarbazole (number average molecular weight 300
000) 5.9 was dissolved in 70ml of tetrahydrofuran to form a charge transfer complex compound. This charge transfer complex compound and 351 g of the above-mentioned Bislade pigment were mixed with a polymethyl methacrylate-styrene copolymer resin (molecular weight 25
0000) 5# was dissolved in 70 dK of tetrahydrofuran and dispersed.

This dispersion was applied onto the undercoat layer and dried to prepare a 20 μm photoreceptor.

The charging characteristics of the photoreceptor thus prepared were measured in the same manner as in Example 1. The results are shown below. However, the charging polarity was set to e.

Vo: e670V Eq: 2.3 Lux+s@e Examples 18-2
7 The photoconductors prepared in Examples 1 to 10 were tested using an electrostatic copying tester (a modified version of the tester used in Example 1) by replacing the 780 nm semiconductor laser and its scanning device 7) with a tungsten light source. In the static method −
The sample was corona charged at 5.5 kV, held in a dark place for 1 second, and then exposed to radar light to examine the charging characteristics. As for the charging characteristics, the surface potential (vo) and the exposure amount (Eq) required to attenuate the potential when dark decaying for 1 second were measured. Next 800n
Eq was measured in the same manner using a semiconductor laser having an emission wavelength of m. Based on this result, the rate of change in exposure amount ΔE (dV-i) between 780 nm and 800 nm0 was calculated. The results are shown in the table.

Comparative Examples 1 to 3 Photoreceptors were prepared in the same manner as in Example 1, except that azo pigments having the following structural formula were used in place of the bisazo pigments in Examples 18 to 27, and evaluated in the same manner as in Example 18. did. The results are shown in Table 5.

Azo Pigment Shop 2M5 As is clear from the comparative example, the photoreceptor using the bisazo pigment of the present invention has high sensitivity and exhibits almost flat sensitivity in the oscillation wavelength range of semiconductor radar.

Example 28 The charge transport layer and charge generation layer of Example 7 were sequentially laminated on the nylon layer of the aluminum base coated with the nylon layer used in Example 17, and the procedure was exactly the same as Example 1 except that the layer structure was different. A photoreceptor was formed, and the charging characteristics were measured in the same manner as in Example 7.

However, the charging polarity was set to e. The results are shown below.

■ o: e 525v Eq: 2.2 AuxΦsec [Effects of the Invention] According to the present invention, by using a specific bisazo pigment in the photosensitive layer, it is possible to improve either the carrier generation efficiency or the carrier transport efficiency inside the photosensitive layer. It is presumed that one or both of them will improve, resulting in high sensitivity and durability.
In particular, an electrophotographic photoreceptor with excellent potential stability during long-term use is constructed. Furthermore, an excellent photoreceptor having practical high sensitivity even in a long wavelength region can be obtained.

Agent Patent Attorney Johei Yamashita

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor having a photosensitive layer containing an azo pigment on a conductive support, the azo pigment has a general formula, ▲a mathematical formula, a chemical formula, a table, etc.▼(1) (In the formula, A and A' each represent a coupler residue having a phenolic hydroxyl group.) An electrophotographic photoreceptor characterized by being a compound represented by the following formula. 2. Both A and A' in general formula (1) are general formulas, ▲ mathematical formulas,
There are chemical formulas, tables, etc. ▼ (2) (wherein, R_1, R
_2 each represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group which may have a substituent, and R_1 and R_2 may form a cyclic amino group together with a nitrogen atom. The electrophotographic photoreceptor according to claim 1, which is a coupler residue represented by the following formula. 3. Both A and A' in general formula (1) are general formulas, ▲mathematical formulas,
There are chemical formulas, tables, etc. ▼ (3) (In the formula, R_3 represents an alkyl group, an aryl group, or an aralkyl group that may have a substituent.) Electrophotographic photoreceptor. 4. Both A and A' in general formula (1) are general formulas, ▲mathematical formulas,
There are chemical formulas, tables, etc. ▼ (4) (In the formula, R_4 represents an alkyl group, an aryl group, or an aralkyl group that may have a substituent.) Photographic photoreceptor. 5. Both A and A' in general formula (1) are general formulas, ▲mathematical formulas,
There are chemical formulas, tables, etc. ▼(5) (In the formula, Y represents a divalent aromatic hydrocarbon group or a heterocyclic divalent group having a nitrogen atom in the ring.) Coupler residue represented by The electrophotographic photoreceptor according to claim 1. 6. Both A and A' in general formula (1) are general formulas, ▲mathematical formulas,
There are chemical formulas, tables, etc. ▼ (6) (In the formula, Y represents a divalent aromatic hydrocarbon group or a heterocyclic divalent group having a nitrogen atom in the ring.) Coupler residue represented by The electrophotographic photoreceptor according to claim 1. 7. Both A and A' in general formula (1) are general formulas, ▲mathematical formulas,
There are chemical formulas, tables, etc. ▼ (7) (wherein, 2. The electrophotographic photoreceptor according to claim 1, wherein R_5 represents an aryl group or a heterocyclic group which may have a substituent. 8. Both A and A' in general formula (1) are general formulas, ▲mathematical formulas,
There are chemical formulas, tables, etc. ▼ (8) (wherein, R_6, R
Each of _7 represents a hydrogen atom, an alkyl group that may have a substituent, an aryl group, an aralkyl group, or a heterocyclic group. The electrophotographic photoreceptor according to claim 1, which is a coupler residue represented by the following formula. 9. The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer containing an azo pigment comprises at least two layers: a charge transport layer and a charge generation layer containing an azo pigment represented by the general formula (1).